My samsung S3mini wont allow me to make calls!???

[sara41h]

I purchased my samsung 4 weeks ago. It worked perfectly for the first 3 weeks, I loved the phone. Then last week as i went to call my friend, dialled her number, pressed the call button, screen "flashes" (i guess) n then goes back to the number, it wont ring or even attempt to make the call. I have done the usual turn it off and back on, wondering has anyone else had a similar problem and what did you do !? Its really starting to hinder my schedule and really just annoy me.